1kW smps project (based on MicrosiM design)

blasphemy000

New member
Hello guys
Is this ringing on my IGBTs?

Transformer input:
View attachment 6476

I wouldn't exactly call that ringing(although it technically kinda is). That looks more like the primary inductance oscillating in combination with the DC blocking capacitance. I've noticed this waveform across the primary of many regulated/current-protected SMPSs, mostly under zero, or fairly light loads. Although, in a SMPS with over-current protection, this waveform can happen when the limiter kicks in(at heavy load) for a short period of time(just a couple switching cycles).

We'll start at the horizontal center of your scope screen and move towards the right; here is my best explanation of this behavior. At the center of the screen the primary switches fully negative, passing current for a specified amount of time. After this, it is switched fully positive. Take notice that this positive section is shorter in time than the negative(either imbalance or more likely regulation/ current limiting kicking in). At about 70% of the way through the positive cycle, it appears that switching stops (0% duty-cycle) and both switches are turned off. Since the transformer was passing current at the time when both switches were turned off, the primary's inductance is holding a current charge that needs to go somewhere. This current will cause oscillations across the primary as it dissipates through the switch's freewheeling diodes and the capacitors at the other end of the primary while it finds it's way back to the DC bus. In furthest right column of your scope screen, it appears that the positive switch tried to turn back on to resume switching, but the limit was hit immediately and it turned back off very quickly. In my experience, a snubber across the primary of the transformer will usually stop this type of oscillation from occurring.
 

Silvio

Member
@ Blasphemy000

A good explanation and most of it might have occurred. I am not against in all you said but this kind of wave shape was experienced while he was using a snubber across the primary or across the collector and emitter of his IGBTs, I do not know exactly where. He also said that when removing the snubber/s this oscillation was gone.

It could also be the fact that he has some long lines going from the trafo secondary to the bridge and output caps. This guy split the pcb in two parts as it came rather cumbersome and big and did not fit in one piece. This all might have occurred due to stray inductance disturbing the gate drive.
 

MicrosiM

Administrator
Staff member
I am not sure if the SMPS was loaded or not when that picture was taken, either I know the running frequency of the converter.
 

Nuhrohim

New member
20171217_001453.jpg20171217_001453.jpg i am from indonesia . So iam sorry if my speak is not better . This is my irs2153d half bridge smps and i have a problem . How to regulated output voltage ?? Thank for answer
 

badboy_6120

New member
Hello
as our dear friend MicrosiM mentioned the smps was not properly loaded when I took the picture
so I install the secondary caps and then remove the snubbers and now everything is completely normal
Thanks anyway
 

MicrosiM

Administrator
Staff member
Hello
as our dear friend MicrosiM mentioned the smps was not properly loaded when I took the picture
so I install the secondary caps and then remove the snubbers and now everything is completely normal
Thanks anyway

That explains everything
 

CDJKuznec

New member
Hello sir MicroSim. Help me please.
I make smps xp-5000. I have 4 transformers e55/28/21core.
1) How there is a lot of turns for primary it is necessary for me? I will reel up a copper strip.
2) How there is a lot of turns for secondary for +/-85v? How many volts will be 1 turn secondary?
3) What frequency of work of kHz will e55/28/21 kernel have if the small operating transformer is assembled 200 turns and 2 on 20 turns?
 

Silvio

Member
Hello sir MicroSim. Help me please.
I make smps xp-5000. I have 4 transformers e55/28/21core.
1) How there is a lot of turns for primary it is necessary for me? I will reel up a copper strip.
2) How there is a lot of turns for secondary for +/-85v? How many volts will be 1 turn secondary?
3) What frequency of work of kHz will e55/28/21 kernel have if the small operating transformer is assembled 200 turns and 2 on 20 turns?

For a core EE55 N87 material frequency 70Khz.

You need to check operating frequency and see that is between 70 and 80 Khz

Your type of smps is self oscillation with small transformer

For input voltage of 210-230-245 Primary turns 9

Primary inductance is 0.517mH

secondary turns for output voltage of 77v-84v-90v = 5 turns

smps not regulated so voltage vary according to input voltage

The voltage on secondary is the peak voltage without load

Volts per turn is according to input voltage AC so for 230v input the bus voltage DC = 230 x 1.414 = 325v /2 = 162v

so 162v / 9 turns = 18v per turn

Rated transformer power is 3500w

Output power is 2040w at 170v 12amps

Regards

Silvio
 

CDJKuznec

New member
Silvio, very big thanks you. I will work on this project. Can i ask some questions to you? Please, sorry me for my bad english, and google translator.
 
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CDJKuznec

New member
Yes you can ask questions I will help you the best I could


Hi Silvio. I need your help. I made smps from Ludo by v2.1 (It is my first smps). My E55/28/21 core.

1) How many turns primary are necessary for me? (AC 220v).
2) How many turns secondary are necessary for me for +/-85v?
3) I have a wire, diameter 0,5mm. How many wires in a bunch are necessary for me for primary and secondary turns?
4) How to have turns wires in a bunch among themselves? To twist in one plait, or to put in parallel how a loop?

How many volts will be 1 turn secondary? (It is necessary +/-12v for fan).

W20NM50 key and stpr1520d diodes.

Very big thanks.
 

CDJKuznec

New member
My smps v2.1 by Ludo

My smps v2.1 by Ludo
 

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Silvio

Member
@CDKUZNEC

Data for EE55 for 1200w Frequency 65Khz B max 1360 guass at max voltage

output voltage minimum 74.5v rated 83.9 maximum 87.5v Output current 8.5 amps at 170 volts
(Note this is the peak voltage observed at the specified input voltage as the smps is not regulated)

copper wire dia 0.5mm for all windings

Input voltage Min 205vac rated 230vac maximum 245vac

Primary winding 2 bundle of 4 wires twisted (total 8 wires) Primary turns 6+5 total 11 turns

Secondary winding 2 bundle of 4 wires twisted (total 8 wires) for each of the dual rail 6+6 turns

You have different voltages for auxiliary windings please take a look at attachment and choose what you like.

A fan will be needed for the amplifier so it is good to make auxiliary winding for power of fan motor 12v or 24v

Volts per turn Approximately = 155v / 11 turns = 14 volts per turn

You can take an idea how to wind a safe transformer please see video on Youtube You can translate in Russian subtitle

LINK https://www.youtube.com/watch?v=_K3ixhcTYFg&t=1s

EE55 RU.JPG

Regards Silvio
 
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